1. Field of the Invention
The present invention relates to a vehicular tire having a carcass, e.g., a radially constructed carcass, with sidewalls and tread, as well as a process of making the vehicular tire and a process of masking an overlapping region of carcass ply ends in the vehicular tire.
2. Discussion of Background Information
Building vehicular tires from several different layers from a radially inwardly direction to a radially outwardly direction is known, e.g., in tires of radial construction having an inner layer, carcass, belt, and tread, and in the side region having an inner layer, carcass, and side part. Further, carcasses of vehicular tires are customarily built from one or more plies of reinforcements which are embedded in rubber parallel to one another. The individual carcass plies in this case are made of continuous rubber strips having reinforcements arranged parallel in the direction of the rubber strip. Depending on the desired bias position or orientation of the reinforcements to the tire equator plane, the rubber strips provided with embedded reinforcements are customarily cut into individual pieces on the bias in the later tire building or crosswise (transversely) for radial carcass building. The uncut sides of the resulting pieces, which previously represented the sides of the rubber strip, are then customarily joined together to form a continuous carcass ply. Thus, as soon as the carcass length desired for the circumference of the tire is achieved, the carcass ply formed from the individual carcass pieces cut on the bias or transversely is laid on the building drum on the previously prepared inner layer, on a carcass layer already placed there, or, if necessary, on additional interlayers. Thus, the carcass ply is laid around the entire circumference and is customarily joined together at its end regions, with individual reinforcements overlapping. Then, depending on the desired design, additional carcass layers, interlayers, belt plies, and tread are applied. During the manufacturing process, it is customary to produce the desired preform shape by expanding the building drum, which has been provided with the carcass plies, in the radial direction during shaping.
After the vulcanization and finishing of the tire, as soon as it is pumped up to its operational state, thickened points produced by the overlapping of several reinforcements in the carcass structure, e.g., in the outer carcass ply, become noticeable, e.g., from the exterior of the tire, and give an unattractive appearance. In this regard, the reinforcements are strongly stretched by the shaping and are shrunk during the subsequent vulcanization, resulting, e.g., in solid carcass regions. As soon as the tire in its mounted state is stressed with internal pressure, this reinforced region exhibits a considerably weaker expansion behavior than the surrounding carcass regions, which results in a differing strength and elasticity behavior of the carcass in this region, and which leads to visible constrictions. This is particularly noticeable when polyester is used for the carcass reinforcements.
Several suggestions have been made for moderating or optically masking the constrictions caused by the overlapping.
EP 0 239 160 B1, e.g., discloses that additional splicing strips can be provided in the region of the overlapping. EP 0 407 134 B1, e.g., discloses laying additional rubber strips in the overlapping region, at least in the region of the bead core. These additional strips serve as elastic cushions in the core region, so that, when there is excess internal pressure, the reinforcements in the overlapping region migrate radially outwardly from the core under elastic compression of the cushion, and, thus, the constriction ought to be largely masked. However, the quality of the masking of the constriction behavior depends upon the thickness of the rubber strip used, and depending upon the thickness of the strip, additional uniformity problems occur due to the additional strip as compared to conventional tires. Further, depending on the thickness of the rubber strip, air inclusions can form on both sides of the strip, i.e:, between the layer covering the rubber strip and the carcass layer. At great expense, e.g., by additional rolling of the layer covering the rubber strip, a distribution of the air inclusions is conceivable, at least when the layers of rubber between the covering layer and the carcass are thin, but the extended covering of the carcass ply by the covering layer prevents a removal of the air inclusions. Insofar as they have been distributed from the immediate region of the rubber strip, they still essentially remain as air inclusions between the carcass and the covering layer and lead to additional problems, e.g., related to the durability of the tire. Owing to the problems that arise, satisfactory coverings of the constrictions with the aid of such an additional rubber strip can only be implemented, if at all, at high additional cost for removal of the air inclusion and for removal of the additional uniformity problems.
The present invention provides a vehicular tire having a carcass, e.g., a radially constructed carcass, with sidewalls and a tread, in which the above-noted constriction effects are simply and reliably masked.
The present invention includes a carcass that, in its sidewall region, is formed of at least one carcass ply having two carcass ply ends and parallel textile reinforcements embedded in the rubber. Further, the at least one carcass ply has at least one overlapping point of the two carcass ply ends, which are overlapped in the circumferential direction of the vehicular tire. The carcass, in its sidewall region, is covered on the outside with a sidewall rubber strip, and a moirxc3xa9 pattern is formed on the sidewall rubber strip from a number of linear elevations associated with, e.g., at least two non-identical families of curves.
The formation of a moirxc3xa9 pattern on the sidewall rubber strip from a number of linear elevations that are to be assigned, e.g., to at least two non-identical families of curves, by the distribution of the intensity of the reflected light as a result of interferences of the line patterns, causes a superposition over a region of possible constriction effects on the tire sidewall such that comparatively small changes in reflection caused by possible constriction effects are difficult to perceive with the naked eye. This can be implemented by simple devices within the scope of tire sidewall decorative design. Thus, implementation is possible without further additional measures in tire building parts or in the tire building process. Thus, the additional measures required in the above-noted documents of EP 0 239 160 B1 and EP 0 407 134 B1, as well as the attendant risks, can be omitted.
The present invention is directed to a vehicular tire that includes a carcass made of rubber, sidewalls, and tread. The carcass, in a sidewall region, includes at least one carcass ply having parallel textile reinforcements embedded in the rubber and two carcass ply ends, and the two carcass ply ends are arranged to overlap in a circumferential direction, thereby forming an overlapping point. A sidewall rubber strip is positioned to cover the carcass in the sidewall region, and a moirxc3xa9 pattern is formed on the sidewall rubber strip.
In accordance with a feature of the invention, the moirxc3xa9 pattern can include a number of linear elevations assigned to at least two non-identical families of curves. At least one family of curves can be formed from curves formed respectively parallel to one another. Further, the at least one family of curves can include at least a two families of curves, and the curves of the at least two families of curves may be formed from curves formed respectively parallel to one another. The curves of the at least two families of curves may be formed from curves formed respectively parallel to one another. Moreover, the two families of curves may intersect one another. Curves of a first of the two families of curves may be formed at an interval r1 to one another, curves of a second of the two families of curves may be formed at an interval r2 to one another, and r1=a*r2, where a is not an integer. Still further, the non-integer value of a can be approximately 1.01xe2x89xa6axe2x89xa61.1.
According to another feature of the invention, the at least one family of curves can include at least a two families of curves, and the curves of at least two families of curves are formed from linear curves formed respectively parallel to one another. Curves of a first of the two families of curves may be formed at an interval r1 to one another, curves of a second of the two families of curves may be formed at an interval r2 to one another, and r1=a*r2, where a is not an integer. Further, the non-integer value of a can be approximately 1.01xe2x89xa6axe2x89xa61.1.
Moreover, the at least one family of curves may be formed from curves formed respectively point-symmetrically. The at least one family of curves can include at least a two families of curves, and both of the at least two families of curves may be formed respectively point-symmetrically. Points of symmetry of the point-symmetric families of curves may be displaced from one another at an interval 1.
Further, the curves of the at least one family of curves can be concentric circles. The at least one family of curves can include at least a two families of curves having curves of concentric circles with a same center. Curves of a first of the two families of curves may be formed at a radial interval r1 to one another, curves of a second of the two families of curves may be formed at a radial interval r2 to one another, and r1=a*r2, where a is not an integer. The non-integer value of a can be approximately 1.01xe2x89xa6axe2x89xa61.1.
The at least one family of curves may be formed as a family of beams through a point of symmetry. Equal angles can be provided between respectively adjacent beams. The at least one family of curves can include at least a two families of curves formed as a family of beams through a same point of symmetry. Adjacent beams of a first of the two families of curves may be formed with a same angle xcex1 between respectively adjacent beams, adjacent beams of a second of the two families of curves may be formed with a same angle xcex2 between adjacent beams, and xcex1=a*xcex2, where b is not an integer. Still further, the non-integer value of a can be approximately 1.01xe2x89xa6axe2x89xa61.1.
According to still another feature of the invention, curves of the at least one family of curves in a two-dimensional system of coordinates (x1; x2) perpendicular to a coordinate line (x1) can intersect it at the zero values of a sine function f(x1)=sin(x10+b*x1) where x10=const, b=const. The at least one family of curves can include at least two families of curves, and curves of a first of the two families of curves in a two-dimensional system of coordinates (x1; x2) perpendicular to a coordinate line (x1) can intersect it at the zero values of a sine function f(x1)=sin(x10+b*x1) where x10=const, b=const, curves of a second of the two families of curves in a two-dimensional system of coordinates (x3; x4) perpendicular to a coordinate line (x3) can intersect it at the zero values of a sine function f(x3)=sin(x30+c*x3) where x30=const, c=const, and at least one of the following are satisfied: (A) one of the systems of coordinates (x1; x2) and (x3; x4) of the families of curves are not identical, (B) phase shifts x10, x30 of the families of curves are not identical, and (C) frequencies b and c of the families of curves are not identical. For the frequencies b and c of the families of curves, b=a*c, where a is not an integer, and the non-integer value of a can be approximately 1.05xe2x89xa6axe2x89xa61.1. For the phase shifts, x10 and x30 of the families of curves, x10=a*x30, where a is not an integer, and the non-integer value of a can be approximately 1.05xe2x89xa6axe2x89xa61.1.
Further, at least one of the two systems of coordinates (x1; x2) and (x3, x4) of the families of curves can be Cartesian coordinate systems, and/or both of the two systems of coordinates of the families of curves can be Cartesian coordinate systems. Further still, at least one of the two systems of coordinates (x1; x2) and (x3, x4) of the families of curves can be curvilinear coordinate systems, and/or both of the two systems of coordinates of the families of curves are curvilinear coordinate systems. Still further, at least one of the two systems of coordinates (x1; x2) and (x3, x4) of the families of curves are polar coordinate systems, and/or both of the two systems of coordinates of the families of curves are polar coordinate systems.
The present invention is directed to a process of making a vehicular tire having a carcass, sidewalls, and tread. The carcass is made of rubber and includes parallel textile reinforcements embedded in the rubber and two carcass ply ends. The process includes circumferentially overlapping the two carcass ply ends of the carcass, thereby forming an overlapping region, covering the overlapping region on the outside with a sidewall rubber strip, and forming a moirxc3xa9 pattern on the sidewall rubber strip.
The present invention is directed to a process of masking an overlapping portion of carcass ply ends in a vehicular tire having a carcass, sidewalls, and tread. The process includes creating a moirxc3xa9 pattern, and forming the moirxc3xa9 pattern on an outside surface of the sidewall in a region of the overlapping portion of the carcass ply ends.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.